Airport lighting control and indication system



March 23, 1948. w. T. PQWELL 2,438,453

AIRPORT LIGHTING CONTROL AND INDICATION SYSTEM Filed Oct. 2, 1944 9 Sheets-Sheet 1 KEY N KEY KEY FLOOD LAM/Kg 9 5 H g H y L F #42490 LAMPS /4 FIG, 34 o o o o c) o o o Q o 0 @41000 LAMP l6 I6 0 Q KE0 a 90 o o 0 R4 M LAMP 0 KEY 0 G/PEA/ LAMP o 5 R50 I70 L a/14W v a 0 "21515 d /CD:IO 0 KEY W o E #42490 LAMPS o o o /7 Qg p 0 o o o q) o Q3 0 WHY .0 0 4 m 0 -/6A7'E LAM/25k m 0 @rwoo LAMP E g /5 s g /5 H KEY- KEY KEY KEY KEY REVOLVING BEACOIV/ [20 2 a E 20 @l W" T FE a INVENTOR.

W/NFREO 7'. POWELL ATTORNEY March 23, 1948.

STEP LINE FIG. .9

w. T. POWELL 2,438,453 AIRPORT LIGHTING CONTROL AND INDICATION SYSTEM Filed Oct. 2, 1944 9 Sheets-Sheet 2 EIEIEJIIIUEIDUUDEI COUNT/N6 RELA Y5 NEAR END FAR E/ID RED Q I 3% 2 TAKE OFF G/fff 7 l6 //6' //7 RED GREE Q a? LAND RED RED I7 EMERGENCY sroP /7 /6' /6a. ms b FIG. 4

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AIRPORT LIGHTING CONTROL AND INDICATION SYSTEM Filed Oct. 2, 1944 9 Sheets-Sheet 5 -5ET-UP I H) I FIG. 7 am I I ST/(41%) t SZMMTL I I I u I I' E] -I a? (51L I I I m J INVENTOR. Wl/VFRED T. POWELL BY A TTORNEY March 23, 1948. w. T. POWELL AIRPORT LIGHTING CONTROL AND INDICATION SYSTEM Filed Oct. 2, 1944 9 Sheets-Sheet 6 STEP LINE 1. AMPJ AMA/AL 0/ F/ a. a

0 4 L 4 a R.n n M N v N0 llllljl l I I I l I I I l l A I I l IIE 0 lllll V T JWI Mr M i|I||| I I I I I I I I I I II D 1 r F A U m n N v .v u W lwlll .1 P WF 1 I ---||.|1|1 IIIIII l1 IIAlIl-ll-llli II I I I I I I l l I I I I I I I I I I Ill M A Ilv 8 5 l llllllll M March 23, 1948. w. T. POWELL 2,438,453

AIRPORT LIGHTING CONTROL AND INDICATION SYSTEM Filed Oct. 2, 1944 9 Sheets-Sheet '7 LAMP y INVENTOR.

W/IVFRED T. POWELL ATTORNEY March 23, 1948. w, POWELL 2,438,453

AIRPORT LIGHTING CONTROL AND INDICATION SYSTEM Filed Oct. 2, 1944 9 She ets-Sheet 9 34- L I/I/E GATE 2 LAMPS LAMPS 2| LAMPS I I mm. sro l /2 LAND I HAZARD I TAKE-OFF I as LAMPS C0 TA 67' LAMPS (-I (-I (-I (-I 4 F 6 2 I l l I I l I I IN VEN TOR.

A TTOR/VEY Patented Mar. 23, 1948 AIRPORT uon'rmo oou'raor. AND mmcs'non SYSTEM Winfred T. Powell, Rochester, N. Y., assignor to Stromberg-Carlson Company, Rochester, N. Y., a corporation of New York Application October 2, 1944, Serial No. 556,800

'1 Claims. (Cl. 177-353) This invention relates to a system for directing by distinctive trafllc lights, the take-off and landing of airplanes on the several intersecting runways of an airport landing field.

The landing field at a typical large airport comprises intersecting runways. For example, two groups of parallel runways may intersect each other at right angles, while two other groups of runways may also intersect each other at right angles but cross the runways of the first two groups at forty-five degree angles. Thus the several runways may extend in almost every direction, to meet various take-of! and landing conditions. With numerous intersecting runways it is essential that traific thereon be carefully directed to prevent confusion and accidents. This direction of traflic is effected by distinctive lights related to the several runways and controlled from a control point or control tower, preferably remotely located with respect to the several runways.

The main feature of the invention relates to the provision of a system of the type above described, in which a minimum number of conductors, preferably only two pairs of conductors, are required between the control tower and the landing field of an airport.

Another feature of the invention relates to simplified interlocking controls which prevent the dispatcher in the tower from setting the trafiic lights at the landing field to direct conflicting trailic.

Other features of the invention will appear from the detailed description and claims when taken with the drawings, in which Fig. 1 illustrates a dispatchers desk provided with a right hand top panel carrying a group of control keys and a left hand top panel bearing a miniature layout of a landing field; Fig. 2 is an enlarged view of the key panel of Fig. 1; Fig. 3 'is an enlarged view of the layout on the left hand panel 01 Fig. 1, illustrating the intersecting runways of a typical landing field, together with the so called gate lamps, flood lamps, hazard lamps and boundary lamps, as well as contact lamps, T-lamps, a

beacon lamp and the lamps associated with the arrows and targets at each end of each runway; Fig. 3A is an enlarged view illustrating the arrangement of colored lamps in one arrow and in its related target, together with a control key as used on the dispatchers desk, it being understood that the arrows and targets at each end of each runway are as illustrated in Fig. 3A; Fig. 4 illustrates the lighted and unlighted conditions of the lamps at the near end and at the far end of each runway when take-cit, land and emergency stop conditions are set up; Fig. 5 is a chart showing the manner in which Figs. 6 to 13 inclusive, are to be arranged in order to disclose the circuits of the control system of the present invention. These figures, with the exception of Figs. 9 and 13, disclose the portion of the control circuits located at the dispatchers desk in the central tower, while Figs. 9 and 13 indicate that portion of the control arrangement located at the landing field which corresponds to similarly identified relays in the tower and with the sufilx I added to relays at the landing field, the detailed circuits of the landing field being omitted since they are duplicates of those employed at the central tower.

The system of the present invention comprises a landing field with its runways and associated trafiic control lights, together with a control center referred to as the control tower. This tower comprises a dispatchers desk 6 bearing a duplicate layout 1, in miniature, of the runways of the landing field and miniature traiiic control lights, as well as related control keys, the lamps being located in the same relation to the miniature runways as those at the landing field. The layout of the landing field has not been illustrated since it is identical except in size with the miniature layout of Fig. 3, and, with the further exception, that the keys shown in this figure, together with the keys Rl to R18, inclusive and the runway relays Rl-2 to RH-I8, inclusive of Figs..6, '7 and 11, are omitted at the landing field. In this connection, even numbered keys R2 to RIB, inclusive of Fig. 11 are part of correspondingly identified even numbered keys-or Fig. 6.

n the miniature layout or the landing field (Fig. 3), as well as the actual landing field (not shown). there are groups or intersecting runways extending in various directions required to meet various take-oi! and landing conditions. By way of example the present layout discloses nine runways although the invention is not limited to this number. Each runway is referred to as having a "near and a far end. Thus the respective ends of one runway are designated Ri and R2. The ends of the remaining runways are designated R3 and R4; R5 and R6; El and R8; R9 and Bill: RH and Eli; Hi3 and Rid; RI! and Hi8; RH and RIB. 0n the miniature layout as well as at the field proper, there are boundary lamps 8 indicating the limits of the field. In addition there is provided a rotating beacon l0, flood lamps ii at the respective corners oi the field and contact lamps l2 outlining each runway. There are also provided so-called T lamps l3, which constitute part of an illuminated rotatable wind direction indicator. Furthermore, both the layout and the actual field are provided with hazard lamps H and gate lamps IS, the latter to indicate loading and unloading positions. Each end of each runway is equipped with an arrow l6 (Fig. 3A) arranged to be lighted in color either by a red lamp Ilia or by a green lamp i812, and is also equipped with a related target, I'l illuminated either by a red lamp Ila or by a green lamp i'lb under the control of key 160. The various keys associated with the respective lamps of the miniature layout control not only the miniature lamps of the layout but also the corresponding lamps at the field proper, since the various keys are omitted from the field as mentioned above.

The right hand portion of the dispatchers desk supports a master panel 20 provided with master control keys and with a busy lamp, which indicates when the system is in operation with the control circuits turned on.

Fig. 4 shows the lighted and unlighted conditions of the target and arrow lamps at the near end and at the far end of a runway when any one of the three following conditions are set up (a) take-oil, (b) land, and (c) emergency stop. Referring to Fig. 3 and assuming that the dispatcher desires to control the lighting on the field for a plane to take oil from runway Rl-RZ, he will operate the key I60 associated with the arrow H5 at the Hi end, which is the condition for marking Ri as the near end and R2 as the far end. If he wants to control a plane on the runway Rl-R2 from the R2 end to the RI end, then he operates the key associated with the arrow at the R2 end which marks this end as the near end.

Then other keys are operated for controlling the flood lamps ll, boundary lamps 9, etc, after which the set-up key i2! is actuated to its Operate position. The system then operates through a cycle to be described and the lamps associated with the selected runway are lighted as indicated in Fig. 4. For example, the green lamp of the target l1 and the red lamp of the arrow it at the near end are lighted and the green lamp of the target Ill at the far end is lighted as a plane is to take of! from this runway. If a plane is to land, then the red lamp of the target and the green lamp of the arrow at the near end are lighted. An emergency stop condition lights mesa-ice the red lamps oi the etc at both ends and the red lamp oi the arrow at the near end.

It will be understood that i control is en= tirely automatic and is controlled by the opera= tion or the key I89 in the it} or the panel in the control tower. It will be observed that eleven counting relays are at the tower to provide the selecting and control conditions and this is done by coding the A and B lines in difierent portions of the counting relay cycle as indicated in Table I which iollows.

The specific layout illustrated in Fig. 3 afi'ords twenty-one different runway combinations conveniently reierred to as stations. The twentyone different combinations or runways or stations may be selected as indicated in Table II which follows. In accordance with Table H for exam ple, the nine runways Rl-RB to Rgll-Rlt inclusive are divided into nine separate stations while the combinations or two runways (plus the last combination of three runways) are divided into the remaining twelve stations. These combinations mean that two or three non-conflicting runways may be selected and th lights set up to control the simultaneous landing or take- 011 of planes on these runways. It will be noted that all of these runway combinations shown at the bottom of Table H are non-conflicting. For example, l-2 and 5-6 are nonconfiicting runways. This combination of two runways is assigned station #10. The X and 0 marks associated with the A and B lines in the first five positions of the counting relay chain indicates the energized and tie-energized conditions respectively of these lines to provide the codes for selecting the stations indicated in the first row, which stations correspond to the runways referred to in the last rows in Table H AR refers to a single lighted runway, BR refers to two runways simultaneously lighted and CR refers to three runways simultaneously lighted.

Team I X=Energized. O=De-energized.

Code

Counter positions Fun e ctlons, Preconditiomng Nwmal A Line a Line 1-2-3-4-5. Select 21 Stations(8ee Table II).

Oil AR Normal 0 OfiL- AR Reverse X On.. BR Normal 0 On. BR Reverse... X 0fl CR Normal 0 0a.. CR Reverse X On.- Boundary Lamps On. X 0n. Boundary Lamps f1 0 OfL. Take Oil X 03. Land 0 On.. Emergency Stop Yes X On Emergency Stop No- 0 0E. Beacon Lamps X 012.. Beacon Lamps Oil 0 On.. T ps On X On.. T Lamps Ofi 0 0a.. Gate 1 amps On-. X 0a.. Gate 1 Lamps 0a.. 0 On.. Gate2Lamps On...-. X 0n. Gate 2 Lamps 0fi. 0 Oil.-. Hazard l Lamps On.- X Ofi. Hazard l Lamps 0a.. 0 0n. Hazard 2 Lamps 0n--. X 011... Hazard2Lamps Oil... 0 Off. Contact Lamps Normal X Oil.... Contact Lamps Dim. X Oil Contact Lamps Brig]: X X Off..- Contact Lamps 0 O 0 On... Flood Lamp 1 0n X 0n. Flood Lamp 2 0n X On. Flood Lamp 3 On X Oil Flood Lamp 4 On X 10 0a.. Flood Lamp l234 On-- X 10 on Enu-nhx X 10 01L Non-Fromlla O Tsar: II

C'Ode for 21 station selection [Positions 1-2-3-4-5] Station l 2 3 4 5 A Line, Position 1... O B Lino, Position 1.. A Line Position 2.. 0 B Line, Position 2... X A Line, Position 3... O X B Line, Position 3. A Line, Position 4- O O B Line, Position 4. A Line, Position 5... 0 O B Line, Position Runways: 7 9 AR 8 10 BR 7 8 9 1O 11 12 13 H 15 16 17 ll 19 no 21 O O 0 x O O O x x x -2. -2- .2. .2- 0 x X 0 O .i. .i. O X x x O O O x O x -i. O O .i. O O X X 0 O O O O O O O O x X 0 (5 21 6 (5 6 I: 6 6 I: I: I: x x X X X X 13 15 17 1 3 3 a 7 7 7 7 ll 13 13 7 14 16 18 2 4 4 4 8 8 8 a 12 14 14 8 5 5 9 15 9 ll 15 17 15 15 17 10 6 6 10 16 10 12 1 18 16 16 18 1g 1 It is believed that the operation of this circuit can be best understood by taking a typical example and describing the circuit operation for this example in detail. It will first be assumed that the operator in the control tower desires to set up the proper condition for a plane to take off from runway Rl'i--i8. Referring to Table II, it will be seen that this runway selection is station #9 and by referring to Fig. 4, it will be seen that the green lamps of both targets and the red lamp of the arrow at the near end (RH) are to be lighted. The operator actuates the key I associated with the arrow 16 at the R91 end of the runway, then actuates the key iZil of the panel. to the take off position and then actuates the set-up key 12! to its operate position. Of course, the other keys will be actuated to control the various other lamp circuits, but

this circuit extending from break contactsv in series of counting relays C4 to Cl, inclusive, conductor I30, make contact of relay L and winding of relay LP to The reason for this circuit for controlling relay LP is to prevent the operation of relay LP until a code determining relay (at left of Fig. 10) has been operated to close a circuit from ground through a make contact of the operated code determining relay to the contact of the L relay. After the first four counting relays have been operated and released, then the coding for station selection has been completed and permanent ground is connected through the back contacts of these first four counting relays to the contact of the L relay because from thisv time on, it is not necessary to hold ofi the operation of relay LP.

Relay LP closes an obvious circuit for operating relay SA and this latter relay closes an obvious circuit for operating relay SAP. Relay SAP closes an obvious circuit for operating kick-off relay KO. A circuit is now closed for operating relay PLP (Fig. 8) which extends from make contact of relay SAP, break contact of relay PL, conductor "I, break contact of relay CH) and winding of relay PLP to The operation of relay SA also applies to the stick I conductor which operates relay UK over a circuit extending from make contact of relay SA, the stick i conductor, break contacts in series of relays CHI to Cl, inclusive and winding of relay CX to Relay LP closes a circuit for energizing the A line conductor which extends from break contacts in series of relays C l to CHI, inclusive, conductor I32, make contact of relay LP, break contact of stick relay STK, conductor I33, lower winding of relay A (Fig. 6), conductor I34, the A line conductor and winding of relay Ai (Fig. 13) to permanently connected to the common return conductor. This is a pre-conditioning impulse and is effective to operate relay A which in turn closes a circuit for relay PC extending from break contacts in series of relays CI, C3, C5, C1, C9 and CH1, make contact of relay CX, conductor i35, make contact of relay A and winding of relay PC to This operates the pre-conditioning relay PC and it in turn closes circuits for operating all 2i of the station relays. This circuit extends from all 2i make contacts of relay PC, conductors l to It, inclusive, highway conductor I36 and upper windings of station relays STI to S'I2i, inclusive, to When relay PLP (Fig. 8) operates, as above described, the step line is opened which is effective to release relays L and LP (Fig. 7) in sequence. The release of relay LP closes a circuit for operating counting relay Ci which extends from break contact of relay LP, make contact of relay SA, pick-up conductor, make contact of relay GK and winding of relay CI to A circuit is now closed for operating relay PL which extends from make contacts of relays Cl and CK in series, conductor 13 and winding of relay PL to Relay PL opens the above described circuit of relay PLP, this latter relay releases and again closes the step line for again operating relays L and LP in sequence. The operation of relay LP effects the release of relay CX by opening up the stick 2 conductor. The release of relay CX opens up and releases relay PL which in turn again energizes relay PLP.

This operation of the L and LP relays, in combination with the PL, PLP and counting relays continues to step these counting relays through their cycle of operations. The operating and release functions of the counting relays are controlled in the'same manner that the counting relays are controlled by the impulsm from the dial in the system disclosed in Powell Patent #232 31 granted August 8, 1948. Re ten-ins to Pics. 8 and 8 ct this patent, it will be observed that the pick-up, stick 1 and stick 3- conductors in the present disclosure, are controlled by relays LP and SA to operate the counting relays in the same manner that conductors ll (pick-up), i5 (stick 2) and i1 (stick 1) are controlled by relays CBP, 28A and SA? to oper-- ate the counting relays in Patent #2325377. in the present system, however, the impulses are provided by the interaction between the counting relays, the LP, PL and PL? relays for providing these impulses in a manner previously explained. Since relays PL and PLP are oi the slow release type, these impulses will be properly timed to provide a series of on" and "oil" impulse periods in the step line circuit. The energized periods or the step line will be referred to as the "on" periods and the tie-energized periods of the step line will be referred to as the "oil" periods. These on and 011" periods are used for effecting the proper controls at the proper times and without overlap between the "on and oh intervals.

From the above. it will be apparent that the pie-conditioning on period (step line energized) is terminated by the operation of relay PLP to mark the beginning of the first "oi!" period (step line tie-energized). Relay PLP next releases to mark the end of the first "oii'" pe= riod and the start of the first on period. Re lay PLP next energizes to mark the and or the first on period and the beginning of the second off period. This continues until the tenth on" period when execution takes place and the circuits are released.

The counting relays are successively operated in successive oii" periods, for example, relay 0! in the first 0E, relay C2 in the second 0 relay C3 in the third ofl," etc. The operated counting relays are released in the second "on period following their operation, ior example, relay C i in the second on, relay C3 in the fourth on," etc. As will be seen from the explanation to follow, during station selection at the first five steps, the A and B lines are conditioned during the "0d" periods, with each condition being executed in the following on" period. Then during the next five steps controls are efiected by energizing or not energizing the A or B line during each on and each "off" period of these steps.

The operation of key 150 of arrow it at the RI! end of runway Bil-Ric, as above described (this key being illustrated as key Ri'l in Fig. 6), closes a circuit irom make contact of relay SAP, break contact of relay STK, make contact of relay STR, conductor I89, break contact of relay KO, make contact of key Ri'i, conductor Md and winding of relay Ell-48 to Relay Bil-i8 operates and closes a locking circuit for itself including its left-hand winding to on conductor I39. It will be understood that the runway keys (Rl to Rid, inclusive) are actuated before the setup key it! is operated, then when relay SAP operates in response to the operation of the setup key, as above described, the selected runway relay (RH-i8, in this example) will be operated and locked before relay K0 is operated.

The circuits of the runway relays (Rt-2 to R||l8, inclusive) are arranged so that no two or more of these relays corresponding to confiicting runways can be left operated. For examon," relay ()2 in the third ple,ass that runway keyhitorltitisactuated at the same time runway key Bil is actuated. This will operate and lock both relays Bic-i8 and Bil-l8. Now when relay KO operates, a circult will he closed for energizing relay Bil-la through its right-hand winding extending from on conductor its, make contact of relay KO, conductor i li, make contact let of relay Rid-it, make contact of relay Bil-i8 and its right-hand winding to Since these windings are diflerentially connected, relay Bil-i8 will be released. This circuit from on conductor it! is extended to all make contacts of all the runway relays except the two shown nearest the coils and the one outside contact of these relays, which contacts are for other purposes. It is not believed necessary to trace out all these circuits in detail, but it will be found that there is a kickwfi circuit provided for preventing the simultaneous energization of runway relays corresponding to conflicting runways when relay K0 is operated.

Reierring back to the operation of the L and LP relays (Fig. '7), when relay LP releases at the end of the pro-conditioning period, the A line is tie-energized and relay A is released. It will be recalled that the operation of relay PC closed circuits for operating all of the ill station or code responsive relays. When relay Cl is operated and also when relay A is released at the end of the pro-conditioning period, the above described operating circuit for relay PC is opened, it releases,

and remains released throughout the remainder of the cycle. Before relay CP releases, however, a locking circuit is closed for all code responsive station relays, which circuit extends from make contact of relay SAP, break contacts of relays L and LP in multiple, conductor M3, upper make contacts of all code responsive station relays and their upper windings to The counting, impulsing and impulse repeating relays now step through their cycles of operations until counting relay Old is operated and counting relay C9 is released. When relay Ciil operates and before relay Ct releases, the circuit is closed for operating relay PL. This circuit extends from break contacts in series of relays Cl C3, C5, fill, make contact of relay 09, make contact of relay Cit, break contacts in series of relays C8, C6, C6, C2, CX, conductor fist) and winding of relay PL to The release of relay C9 opens up the above described circuit which effects the release of relay PL, but the release of relay PL at the end of the cycle does not close a circuit for operating relay PLP because its circuit is now open at a break contact of relay Clli and a make contact of relay 09. Consequently, the step line is not opened, thus leaving relays L, LP, SA, SAP, K0 and Cid energized until the operator restores the setup key B2B for releasing relay STR. Proceeding now with thecoding portion of the circult for selecting station #9, it will be explained how all of the station relays, except relay 8T9, are dropped out during the first five steps of the cycle for selecting station #9 by leaving this particular relay energized through the remainder of the cycle. From Table II it will be observed that the only code impulse applied to the A or B lines when station #9 is selected is an impulse applied to the A line in position 5 which is step 5 of the counting relays. This means thatstepping will proceed without either relay A or relay B being operated until the fifth step of the cycle.

The code determining relays (Fig. 10) record the condition at each step by means of the op eration of an AX relay at the beginning or the "on period it the A line is energized, by the operation of a BX relay at the on period if the B line is energized and by the operation of an O relay at the on" period if neither line is energized. Since neither the A nor the B relay is energized at the first on" period, a circuit is closed for operating relay I-O which extends from make contact of relay PL, conductor I44, break contact of relay PLP, break contacts in series of relays C6, C5, C4, C3, C2, make contact of relay I, conductor I 45, break contacts in series of relays A and B, conductor I-O, highway I46, conductor I-0 and winding of relay I-O to Thus the code determining relay is operated when relay PLP releases to energize the stepline and mark the beginning or the on period. Now when relay PL releases, the above described operating circuit for the code determining relay is opened, but this relay is now locked through its left-hand contact, conductor I4'I, make contacts of relay L and make contact of relay SAP to With relays L and LP operated, the break contact of the make before break combination of relay L and the associated break contact of relay LP are opened, which opens the locking circuits of the code responsive station relays including conductor I43 and the make contacts of these station relays. At this time another locking circuit is completed through the make contact of the make before break combination of relay L to the contacts of the code determining relays. Since relay I-O is operated, this locking circuit extends from make contacts of relays SAP and L, conductor I48, make contacts of relay I-O, conductors 3 to 9, inclusive and I4 to 2i, inclusive, highway I49. conductors 3 to 9, inclusive and I4 to 2|, inclusive, make contacts and lower windings of relays ST3 to ST9, inclusive and STI4 to STZI, inclusive to for locking these station relays. Station relays STI, ST2, S'I'lll, STII, STI2 and STI3 are released because at this time no locking circuits for these relays are completed. Now when relay L releases, the lock ng circuit, including the upper make contacts of the station relays and conductor I43, is completed for holding those relays which were left operated in response to the first code above described.

The release of relay L at the end of the first code (first on eriod) releases relay I-O by openin its locking circuit. since relay PLP is now in its operated position for o ening the above described operating circuit for relay I-O, When relay PLP next releases, after the operation of relay PL (during the second off period) the next code determining relay is actuated. Since neit er the A nor the B line is energ zed for the second code. relay 2-0 will be operated over the above described circuit extending from on conductor I 44. break contacts in series of relays PLP, C5 to C3. inclusive, make contact of relay C2, conductor I50, break contacts of the A and B relays. conductor 2-0, highway I46, conductor 2-0 and winding of relay 2-0 to Now when relays L and LP operate at the beginning of the second on period, the locking circuits of the station relays, including conductor I43, are opened. The second code will now be effective to drop out another group of ST relays. In this instance, since relay 2-0 is operated. relays ST3, ST4, STIII to STI'I, inclusive and ST2I have no locking circuits and will be released, thus leaving relays ST5 to S'IB, inclusive and STI-fl to ST20,

10 inclusive, still operated. The locking circuits for relays ST5 to STS, inclusive and BTIS to ST20, inclusive include conductor I48 and make contacts of relay 2-0. Relay 2-0 is released by the release of relay L in the same manner as described for releasing relay I O.

Sinc neither the A nor the B line is energized for the third code (counting relay C3 operated), relay 3-0 will be operated through break contacts of relays A and B. Now when relays L and LP are operated to open the locking circuits of the code responsive station relays, including their upper contacts, another group of these station relays will be released as determined by the circuits through the code determining relay. In this instance, the locking circuits to the lower windings of the station relays by way of make contacts of relay 3-0, include relays STI to STS, inclusive, S'II9 and BT20 or those left operated from the preceding codes, thus relays ST5, STE and STIB are released. The fourth code is likewise an open condition of both A and B lines, consequently relay 4-0 isoperated and when relays L and LP next operate to execute this code, the only relays of those left operated and controlled through contacts of relays 4-0 are relays ST8 and STS, thus releasing relays ST1, ST I9 and ST 20. Relay LP will be operated at this time over a circuit extending from make contact of relay 4-0, conductor I53, make contact of relay L and winding of relay LP to Relay 4-0 is released when relay L releases at the beginning of the fifth "off period for deenergizing conductor I".

At the fifth code the A line is energized over a circuit which extends from make contact of relay SAP, make contact of relay PL, break contact of relay LP, conductor I32, break contacts in series of relays CIO to C6, inclusive, make contact of relay C5, conductor I5I, make contact of relays BIT-I8, conductor I 52 and lower winding of relay A to the A line. This operates relay A. The A line is de-energized to release relay A when relay LP is operated at the beginning of the fifth on period to open the above described circuit.

Relay SAX is now operated over a circuit extendin from make contact of relay PL, conductor I44. break contact of relay PLP. break contact of relay C6, make contact of relay C5, conductor I54, make contact of relay A, conductor 5AX, highway I46, conductor SAX and winding of relay SAX to Relay SAX is locked operated, after this circuit is opened by the re lease of relay PL, the'locking circuit extending over conductor I41 and make contacts of relay L.

Recalling that relays ST8 and 8T9 are the only station relays now operated. the fifth code is effective to release relay ST8 and leave relay ST9 energized. Relay ST8 is released when relays L and LP operate to open conductor I43 because the locking circuit for the lower winding of relay ST8 is not extended to a contact of relay SAX. There is a locking circuit, however, through the 5AX relay to the ST9 relay for maintaining this relay locked. This circuit extends from make contact of relay SAP, make contacts of relay L, conductor I48, make contact of relay SAX, conductor 9, highway I49, conductor 9, make contact and lower winding of relay ST9 to When relay L is next released to terminate the fifth code (which happens before relay SAX is released), the locking circuit for relay ST! is completed by way of its upper winding and conductor I 4.3, Before relay L next operates, relay STK is operated over a circuit extending from make contact of relay PL, conductor 4, break contact of relay PLP, make contact of relay C6, conductor I55, break contact and winding of relay STK to Relay STK closes a locking circuit for itself extending from make contact of relay SAP, make contact and winding of relay STK to The operation of relay STK extends conductor I43 to at a make contact of relay SAP for providing a permanent locking circuit for the station relay until all circuits are cleared out.

It might be again pointed out at this time that the relays at the landing field corresponding to those relays at the tower are operated in the same manner over similar circuits and in synchronism with those at the tower just described. The circuits of the landing field relays are not shown, but certain of them are indicated and given reference characters corresponding to similar relays in the tower, but with the subscript I added. Furthermore, it will be seen that the station relays are code responsive relays since they respond to codes by either remaining operated or dropping out, in the manner just described.

Station #9 has been selected and it now remains to operate the proper lamps associated with this station, which is runway Hill-R18. The upper set of 8 make contacts associated with relay ST9 lead to the arrow and target lamps for this runway (as indicated by the red and green lamp symbols R and G, respectively) and these lamps are controlled by the condition of control relays NR, TOL and ES (Fig. 11), when execution takes place for operating executing relay EX at the end of the cycle, at which time counting relay C It] will be in its operated position. The circuit for operating relay EX extends from make contact of relay LP, conductor 3!, make contact of relay A, conductor 30, break contacts in series of relays C5 to C9, inclusive, make contact of relay Iii, conductor W6 and winding of relay EX to It will be understood that the circuits from these control relays lead in multiple to all the code responsive station relays, where they are extended by the operation of a particular code responsive station relay to the arrows and targets of the associated station or runway. These contacts have only been shown on relay STt for the sake of simplicity, but it will be understood that the same number of contacts appear on all station relays. only one of which is left in its operated condition when execution takes place, This multiple connection is indicated by theusual short tie line which indicates a common connection to contacts of other relays,

It will now be explained how the lights are controlled in accordance with the condition set up by the dispatcher, assuming station #9 selected. After the fifth code has been recorded, as above described for leaving relay ST9 operated, the counting relay chain steps through positions 6 to ill, inclusive. Each of these steps is divided into a separate and distinct"o and on period, with no overlap, so that two codes can be transmitted by way of the A and B lines at each step. In the above example it was assumed that the operator actuated the controlling key IZO to its take-off position and since the key associated with arrow Rl'l was operated, the runway RllR-l8 is set up for controlling the take-ofi in the normal direction, that is, from the RI! end to the RIB end. It will be understood that the contacts ofkeys R2, R4, R5, R8, RID, Rl2, RM, RIB, RIB at the t p of g 10 and 11 are controlled by the keys with corresponding reference characters shown at the right of Fig. 6. With counting relay C6 operated and relays PL and PLP operated (#6 "01? period), a circuit is extended to the A line for energizing or not energizing this line in accordance with the normal or reverse control respectively of the selected runway. This circuit may be traced from make contact of relay PL, conductor it, make contact of relay PLP, break contacts in series of relays Cifl to C7, inclusive, make contact of relay C6 and conductor 31 to key Rid. If key Rig is not operated and key RH is operated, the A line is not energized since the control is for runway Rll to RIB. It will be obvious that the operation of key R18 operates relay Rli-lt for selecting this same runway in the manner above described, but in the latter instance the closure of the RH; contact establishes a circuit for energizing the A line during the sixth ofi period. This circuit is from conductor 37 (above traced) make contact of key R18 (Fig. 11), conductor H33, lower winding of relay A, conductor i3 5, A line, winding of relay Al and common return to Relays A and Al are operated and a circuit is closed for operating relay NR (Fig. 11) which extends from break contact of relay LP, conductor 32, make contact of relay A, conductor 33, break contacts of relays Clll to Cl, inclusive, make contact of relay C6, conductor l5?! and winding of relay NR to Relay NR is locked to at a make contact of relay SAP until the circuits are cleared out by the restoring or the set-up key. It will be understood that relay Al controls similar circuits at the landing field.

When the system advances to the sixth "on position, relay C5 will be released and since relay CS is operated at this time, a circuit is completed for controlling the BR runways (which is the condition for the simultaneous control of two runways as indicated in Table II) in the same manner that the AR runways are controlled as now being described. When the system advances to the seventh ofi position the control cricuit is extended through a make contact of relay C1 to a make contact of relay A to determine if relay A is operated or not in accordance with the code for this position. This also applies to relay A8 at the landing field.

With the systemin its sixth ofi position the B line is energized or not in accordance with whether or not the beacon lamps are to be lighted. If they are to be lighted, a circuit may be traced for operating relay BCN which extends from break contact of relay LP, conductor 32, make contactof relay B, conductor 36, break contacts in series of relays Cill to Cl, inclusive, make contact of relay C8, conductor 35 and winding of relay BCN to Relay BCN locks itself operated by way of conductor I58. This circuit requires the energization of the B relay and this relay will be energized when the key which controls the beacon lamp is operated, the circuit being traced from make contact of relay PL, conductor M4, make contact of relay PLP, conductor 38, break contacts in series of relays CH) to C1, inclusive, make contact of relay C6, conductor 31 and beacon lamp key to conductor H50 which extends through the B and Bi relays and the B line in series. The operation of the BCN relay, or any other of these control relays, closes a locking circuit by way of conductor I58 and the contact ofv the operated relay, which amass 13 maintains the operated relay energized until the circuits are cleared out.

It is believed that the above typical examples of how these lamp control relays are controlled I will be sufllcient to provide a complete understanding of the control of these relays at the various steps of the system, since the complete circuits for the control tower are illustrated. Since it was assumed that a take-oil" condition is to be controlled in the normal direction for runway Ri lR| 8, it will now be pointed out how the control lamps are selected and energized. Relay NR is operated as already described and relay TOL is operated because the take-oi!" key contact I26 is closed in its lower position (Fig. 12). This circuit may be traced from make contact of relay PL, conductor i, make contact of relay PLP, conductor 36, break contacts in series of relays CM and C9, make contact of relay C8, conductor 38 and make contact oi take-off key I20 to conductor I33 for energizing the A line and relays A and AI in the eighth oiT" period. With relay A energized, relay TOL at the tower (and also at the landing field) is energized over a circuit which may be traced from break contact of relay LP, conductor 32, make contact of relay A, conductor 33, break contacts in series of relays Gill and C8, make contact of relay C8, conductor 39 and winding of relay TOL to It will be obvious that relay TOL is not energized when the key is left in its land position because the A line is not energized for completing the circuit to relay TOLL The emergency stop condition is set up when key (25 is operated to the emergency stop" position (upper) for energizing the A line during the eighth on period, which is eifective to operate and lock emergency stop relay ES. This circuit may be traced from make contact of relay LP, conductor 3i, make contact of relay A, conductor 30, break contacts in series of relays C5, C6, C1, make contact of relay CB, conductor lGi and winding of relay ES to The two hazard lamp circuits #1 and #2 are controlled by energizing or not energizing the B line in the eighth "oif and eighth "on periods, respectively. The contact lamps are lighted, not lighted, lighted dimly, normally or brightly in accordance with the conditioning of the CLN and CLD relays (Fig. 12) in the ninth "oiY period in a manner which will be obvious from the circuit shown and from the description the control of other relays dur ng other oil? and on periods of the cycle. The four flood lamps are controlled individually or in combination by energizing or not energizing the A and B lines in the ninth "on period and by energizing or not energizing the A and B lines in the tenth "05 period, all in a manner which will be obvious from the preceding explanation.

When the counting relays take their tenth step and advance into the tenth on" position (release of relays PLP and C9 and before relay PL releases), execution takes place it the setup key is in its operate pos tion. This circuit may be traced from make contact of relay PIl, conductor I44, break contact of relay PLP, make contact of relay Cill, break contact of relay Cl, setup key i2l, conductor I33, winding of relay A, conductor I34, A line, winding of relay Al and common return to This operates the A relays for closing a circuit for operating relay EX which may be traced from make contact of relay LP, conductor 3|, make contact of relay A, conductor 30, break contacts in series of relays CI to Cl, inclusive, make contact oi relay Cit, conductor I and winding of relay EX to Relay EX locks to on conductor "58 and a circuit is now closed for lighting the lamps as selected by the control relays. In the present example, this circuit extends from make contact of relay EX, break contact of relay ES, inner lower make contact of relay TOL and make contact-oi relay ST! to the green lamp in the target at the far (RIB) end of the selected runway. The circuit for the green lamp in the near (Ril) end of. the selected runway extends from the outer lower make contact of relay TOL and a make contact oi. relay ST! to this green lamp. The circuit for the red lamp associated with the arrow at the near (RH) end of the selected runway extends through the lower middle make contact of relay TOL, the lower middle break contact of relay NR and make contact of relay 5T8 to this lamp. It will be observed that this is the condition shown in Fig. 4 for controlling the "take-on and since station #9 has been selected, runway Bil-Rid is the only one at which the lights are energized.

The operation of relay EX also applies by way of conductor I62, to the other control relay contacts Ior lighting the other lamps or not lighting these lamps, in accordance with whether or not the associated relays have been operated, such as the flood lamp relays FLI to FL, inclusive, the beacon lamp relays BCN, the boundary lamp relays BN, etc. Relay EX remains operated for controlling the lighting of the selected lamps until the dispatcher restores the setup key I to normal. This operation releases relay STR which opens up the stepping line for releasing relays L, LP, SA, CH) SAP, K0 and STK in sequence. The release of relay SAP effects the release of relay EX and any of the control relays which were operated during the cycle.

It is believed that the above examples are sufficient to give a complete understanding of the operation or the system for controlling the various circuits. It will be understood that the selection of any one stat on relay above 8T9 operates to select two or three simultaneous runways in accordance with the particular station selected. This means that the controls are eiiective to control take-oil, land or "emergency stop conditions for these runways in normal or reverse in accordance with the keys which are operated on the control panel in the tower. It will be seen from the above explanat on that the A line on conditioning periods are used for controlling certain relays (EN, BS, etc.) over conductor an and that the A line "01?! conditioning periods are used for controlling certain other relays (NR, TOL, etc.) over conductor 33. The #6 A line 011" condition (conductor I62) and the #7 A line oil? condition (conductor I63) has not been shown wired to any relay circuit. This means that these positions are reserved for the BR and CR runway combinations shown in Table II and may be connected to NR relays at these positions for controlling the combinations of runways in a manner shown for the AR runway control.

It is believed that another example of the station selection code arrangement will be helpful in understanding just how these code responsive station relays are released in response to the various codes, leaving only the desired one energized after the first 5 codes have been transmitted. Recalling that all 2| station relays are operated during the pie-conditioning period, it

will now be assumed that runway relay Ri--2 is energized in response to the operation of either key RI orkey R2 for selecting runway Ri-RZ. Referring to Table II it will be seen that the A line is energized in position i and this is the only energization of either line during'the five periods or positions when station #1 is to be selected.

The energlzation of the A line operates relay A during the first 03" period of the cycle over a circuit extending from make contact of relay SAP, make contact of relay PL, break contact of relay LP, conductor use, break contacts in series of relays CW to C2, inclusive, make contact of relay Cl, conductor i6 1", make contact of relay Rl-2, conductor E52, conductor I33, lower wind ng of relay A, conductor Kid, A line, winding of relay AI and common return to (l. Relay A is locked operated by the operation of relay L at the beginning of the first on" period of the cycle over a circuit extending from make contact of relay SAP, make contacts of relay L, break contact of relay STK, conductor I65,

make contact and upper winding of relay A to v Consequently, relay A remains locked operated until relay L is released at the end of the first on period. Relay i'AX is now operated,

when relay FL? is released, over a circuit extending from make contact of relay PL, conductor I, break contact of relay PLP, break contacts in series of relays C6 to C2 inclusive, make contact of relay Cl, conductor M5, make contact of relay A, conductor iAX, highway H35, conductor IAX and winding of relay ME to Relay IAX is locked operated'through a make contact of relay L until the end of the first "on" period when relay LP is released. Since neither the A nor the B line is energized at positions 2, 3, 4 or 5 for selecting station relay STI, relays 2-0, 3-0, l-O, and 50 will be operated over break contacts of relays A and B when the counters g0 throughthese five positions. Now when relay LP is operated at the beginning of the first on period, the first code test is made by way of the c rcuits through the code determining relays. Since relay iAX is operated, a circuit is closed through the make before break contact of relay L and conductor I48 to the make contacts of relay MK and since these mak contacts extend only to the locking circuits of code responsive station relays ST! and STIB, all station relays are released at this tme except STi and STlil.

The ST! relay is released when the second code is tested or executed because relay 2-0 is operated at'this time and'the looking circuit for the station relays completed through make contacts of relay 2-0, only extends to one of the two relays left operated from the previous code, that is, to relay STI by way of conductor 1 in highway I49.

The execution ofthe third code through relay 30 is completed to relay STI, the execution of the fourth code is completed through a make contact of relay 4-0 to relay ST! and the execution of the fifth code is completed through a make contact of relay 5-0 to relay STI. Consequently, only relay SI! of the 21 code responsive relays, operated at the beginning of the cycle, is left operated after the transmission of the five coded impulses.

Comparing Table II with the circuits of the code responsive relays will indicate how the energized (X) and the de-energized (0) conditions of the A and B lines at the five code steps are efiective to complete circuits for the required code responsive station relays throughout the five steps by way of the code determining relay contacts. In this connection, it will be remembered that the AX relay is operated in response to a code corresponding to the A line energization, the BX relay is operated in response to the B line energization andthe O relay is operated in response to neither the A nor the B line being eneirgized at the corresponding steps of the code ser es.

What I claim is:

1. In a trafic control system for an airport or the like, a landing field provided with intersecting runways, directive signals for indicating which ends of the runways shall be used as entrances and which ends shall be used as exits, a control tower provided with selectively operated keys at said tower related to the signals located at said field, conductors connecting said tower and said field, a group of relays at said field, said group of relays controlling the selective actuation of the directive signals associated therewith, and means including said conductors controlled by the selective operation of said keys for operating all of the group relays and then selectively releasing all of said group relays except predetermined ones thereof controlling desired signals.

2. In a trafic control system for an airport or the like, a landing field provided with intersecting runways, directive signals for indicating which ends of the runways shall be used as entrances and which ends shall be used as exits, a control tower provided with selectively operated keys related to the signals located thereat, runway relays operated by said keys, said runway relays having windings arranged to be differentially con- "nected when two relays associated with coniiicting runways are operated whereby one runway relay related to a conflicting runway is released, a set of conductors connecting said tower and said field, a group of relays at said field, said group of relays controlling the selective actuation of the directive signals associated therewith, and means including said conductors and controlled by the operation of said runway relays for selectively operating said groups of relays.

3. In a tramc directing system for airports or the like in which there are a plurality of runways with lights controlled by series of coded impulses transmitted over a line circuit for controlling traiiic either way over the associated runways, a number of code determining relays each corresponding to one of said runways, a number of code'responsive relays each corresponding to one of said runways, means for selectively operating one of said code determining relays, means for simultaneously operating all of said code responsive relays,'means for holding the operated one of said code determining relays during the transmission of a series of coded impulses, means for releasing all but one of said code responsive relays during the transmission of said series of coded impulses, and means including said one of said code responsive relays for selecting and operating the lights of one and only one of said runways.

4. In a traffic directing system for airports or the like in which there are a plurality of runways with lights controlled by series of coded impulses transmitted over a line circuit for controlling traffic either way over the associated runways, a niunber of code determining relays each corresponding to one of said runways, a number of code responsiverelays which number is greater than the number of impulses in any one of said series each relay corresponding to one of said runways, means for selectively operating one of said code' detern'lining' relays, means for simultaneously operating all. of said code responsive relays, means for holding the operated one of said code determining relays during the transmission of a series of coded impulses, means for releasing all but one 01' said code responsive relays during the transmission of said series of coded impulses, and means including said one of said code responsive relays for selecting and operating the lights of one and only one of said runways.

5. In a traflic directing system for airports or the like in which there are a plurality of runways with lights controlled by series ot coded impulses transmitted over a line circuit for controlling traflic either way over the associated runways, a number 01' code determining relays each corresponding to one of said runways, a number of code responsive relays which number is greater than the number of impulses in any one or said series each relay corresponding to one of said runways, means for selectively operating one of said code determining relays, means for simultaneously operating all of said code responsive relays, means for holding the operated one of said code determining relays during the transmission of a series of coded impulses, means for releasing all but one of said code responsive relays during the transmission of said series of coded impulses, means including said one of said code responsive relays for selecting and operating the lights of one and only one of said runways, and means controlled over said line circuit for selectively displaying the lights of a selected runway ior indicating the direction of trafllc thereover.

8. In a station selecting system, a sending location and. receiving location, a station key at the sending location for each station, a station relay at the receiving location for each station, means controlled by the operation of one of said station keys for operating all of said station relays, and means controlled by a number of impulses which is less than half the number of said station relays for'releaslng all of the operated relays except one, whereby one of said stations at said receiving location is selected.

7. A control system for an airport comprising a plurality of runways certain oi. said runways conflicting with other runways, a control relay for each runway, means for operating a plurality of said relays, and means including contacts on one of said operated relays and contacts on any other operated relay representing a runway conflicting with that of said one relay for releasing said one relay.

WINFRED T. POWELL.

REFERENCES CITED The following references are 01' record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,051,419 Preston Aug. 18, 1936 2,113,383 Powell Apr. 5, 1938 2,169,480 Preston Aug. 15, 1939 2,216,610 Culbertson Oct. 1, 1940 2,248,822 Quinby July 8, 1941 2,265,310 Pickell Dec. 9, 1941 2,296,941 Molnar Sept. 29, 1942 2,298,946 Judge Oct. 13, 1942 2,344,759 Wight Mar. 21, 1944 

